1. Field of the Invention
This invention relates to a new and improved ram drive chuck which is particularly, though by no means exclusively, adapted for use in the controlled, driven winding and/or unwinding of large, relatively heavy rolls of material.
2. Description of the Prior Art
Although a wide variety of drive chucks are, of course, known in the prior art, none are known to applicants which can function to both positively engage and disengage, as by inward and outward ramming, and drive, a workpiece in the carefully controlled, safe and particularly effective manner described in detail hereinbelow. More specifically, and taking for example the safety drive chucks as disclosed in our commonly owned U.S. Pat. Nos. 3,777,999 and 4,105,171--which United States Patents represent the most relevant prior art known to applicants--it may readily be seen that, although those drive chucks operate remarkably well in the performance of the disclosed functions thereof, i.e. the absolutely safe drive of workpieces such as driven shafts even under conditions of high drive chuck torque loadings, no capability is included therein for the automatic and positive engagement and disengagement thereof with the workpiece to be driven thereby. Too, and although a variety of devices are, of course, known which operate to ram a workpiece into engagement with a drive chuck or like drive means, no such device is known which combines the ramming and driving functions in the carefully controlled, safe and particularly effective manner of the ram drive chuck of our invention.